Recycled Synthetic Turf and Infill Product

ABSTRACT

Disclosed herein is a method for recycling synthetic turf that includes combining a plurality of synthetic turf fragments with additives to form a mixture and extruding the mixture. The method produces a recycled material suitable for use as infill in a synthetic turf. Accordingly, an infill for synthetic turf and a synthetic turf including that infill are disclosed herein.

CROSS-REFERENCE(S) TO RELATED APPLICATION(S)

This application claims priority to and is a divisional of U.S. patentapplication Ser. No. 13/672,227 entitled “METHOD OF RECYCLING SYNTHETICTURF” which was filed on Nov. 8, 2012; U.S. patent application Ser. No.13/672,227 claims priority to U.S. Provisional Patent Application Ser.No. 61/557,073, now expired, entitled “METHOD OF RECYCLING SYNTHETICTURF” which was filed on Nov. 8, 2011, and U.S. patent application Ser.No. 13/672,227 is a continuation in part of U.S. patent application Ser.No. 12/638,656 entitled “METHOD OF RECYCLING SYNTHETIC TURF AND INFILLPRODUCT” which was filed on Dec. 15, 2009; U.S. patent application Ser.No. 12/638,656 claims priority to U.S. Provisional Application No.61/122,592, now expired, entitled “METHOD OF RECYCLING SYNTHETIC TURF”which was filed on Dec. 15, 2008, the entireties of which are herebyincorporated by reference.

FIELD

This application is related to the field of synthetic turf, and moreparticularly to methods of recycling synthetic turf and related infillmaterials.

BACKGROUND

Synthetic turf has been used for years in athletic playing surfaces suchas football, baseball, and soccer fields, and has more recently beenused in other applications where an alternative to natural grass isdesired. These applications include, for example, playgrounds,residential and commercial lawns, landscaping, jogging paths, paintballfields, tennis courts, putting greens, and dog runs. Typically,synthetic turf includes a pile fabric having a backing and a pluralityof upstanding ribbons, also called face fibers or filiform formations,resembling natural grass. Many synthetic turf products also include aninfill material dispersed among the upstanding ribbons, which mayinclude sand, tire rubber crumb, and/or other particulates, eithersingularly or in combination with each other. The infill materialsimulates soil in natural turf, acts as a ballast, and/or contributes tothe physical properties of the turf, such as resiliency, that make theturf suitable for a particular use.

Synthetic turf has a limited useful life, the length of which depends onthe construction of the turf, the application for which it is used, andhow the turf is maintained. As an example, a typical synthetic turf foruse as an athletic field may have a useful life of from about 8 to 15years. A large amount of synthetic turf is currently being used inhundreds of athletic fields and in other applications. To avoid sendingthat turf to landfills at the end of its useful life, there is a needfor a method of recycling and reusing all or portions of the syntheticturf. There is also a need for a synthetic turf that is recyclable.

Recycling of a product typically refers to converting that product intoa material or product for another use or extracting at least one of theindividual components or materials of the product for use of thatcomponent or material in another product. The recycled product may beused in a similar product, such as when paper products are recycled tomake other paper products, or may be used in a completely differentproduct, such as when tires are recycled to make asphalt.

Methods for recycling carpet and for preparing carpet backing usingrecycled carpet scrap are known. Some such methods involve separatingthe carpet yarns, or tufts, from the backing, for example by cutting,and processing only the tufts to recover any nylon. In another recyclingprocess the tufts can be spun into a new yarn for use in carpet or othertextiles. One problem with these methods is that only the face fibersare recycled and the backing must be otherwise disposed of. Othermethods of recycling carpets include grinding carpet scrap, includingthe backing, into a fine powder. The powder is then introduced into acarpet backing formulation which may be used as, for example, a precoat,laminate coating, skip coating, or foam coating. The formulation is thenapplied to a substrate, and cured by heating or drying. One problem withthese processes for recycling carpet is that recycled material can makeup only about 5% by weight of the carpet backing into which the recycledmaterial is incorporated. This corresponds to approximately 2.5% byweight of a broadloom carpet.

Synthetic turf differs in composition from carpet, and those differencesin composition make conventional carpet recycling processes unsuitablefor recycling synthetic turf. The majority of carpet products use nylonface fibers, while the majority of current synthetic turf products usepolyethylene. The primary coating of most broadloom carpet is a latexcoating, while the primary coating in most synthetic turf ispolyurethane. In the United States, only a small fraction of broadloomcarpet includes a coating containing polyurethane, and only a smallfraction of synthetic turfs have a coating containing latex.

Most of the synthetic turf manufactured in recent years has had apolyurethane coating applied to the backing There is a belief thatpolyurethane coated synthetic turf as a whole cannot be recycled. Thisis because the polyurethane coating, according to conventional wisdom,cannot be recycled. Polyurethane is thermoset (versus thermoplastic) andis therefore difficult and costly to recycle. Polyurethane is thereaction product of a polyol and an isocyanate. When these chemicals aremixed together and cured they form a solid polyurethane. The combinationis applied to the backing of a tufted material for the purpose oflocking the face fibers into the primary backing. An additional coatingof a hot melt adhesive or a polyurethane foam can also be applied. Thissecondary coating is typically used to attach a secondary backing whichcan be polyester or polypropylene.

Many synthetic turf products include components that are not found incarpet and that are incompatible with, or at least undesirable in,conventional carpet recycling methods. For example, conventional carpetdoes not include infill. Typical infill materials for synthetic turfinstallations include sand, tire rubber crumb, and/or otherparticulates, either singularly or in combination with each other. Thus,recycling synthetic turf presents a unique problem not encountered inthe recycling of carpet. Separating infill from the remainder of theturf may require use of special equipment, and there may beenvironmental concerns associated with disposing of the separatedinfill. Additional concerns in the recycling process are the effect ofany residual infill particulates on the size reduction process and onthe properties of the final product.

Conventional carpet recycling methods provide end products that areinconsistent with or that are not ideal uses of recycled synthetic turf.For example, nylon carpet recycling is focused primarily on separatingand recovering the nylon, which is of greater value than other carpetcomponents. In contrast, current synthetic turf typically containslittle or no nylon. Additionally, conventional carpet recycling methodsproduce, as described above, a dry powder that can be incorporated insmall amounts into carpet backings. Alternatively, for synthetic turfrecycling, it is desirable to recover and reuse most or all of thesynthetic turf, and to do so in a way that the recycled synthetic turfmakes up a large percentage of the turf into which it is incorporated.

There remains a need for an improved method of recycling and reusing anexisting synthetic turf, or at least a portion of an existing syntheticturf, to avoid sending the entire synthetic turf to a landfill when itis no longer useful. There is also a need for a synthetic turf that canbe recycled and reused.

SUMMARY

A method of recycling synthetic turf into a product that can be used ina variety of applications including as synthetic turf infill isdisclosed. The method includes the steps of (a) combining a plurality ofsynthetic turf fragments with at least one modifier, filler, or colorantto form a mixture; (b) extruding the mixture to form an extrudate; and(c) cutting the extrudate into pieces.

In one embodiment, the modifier is selected from the group consisting ofpolypropylene, polyethylene, rubber, Exxon Vistamaxx 3000, Exxon PX9361,Exxon PX 9371, Faraprene 381-35A, and combinations thereof. In anotherembodiment, the filler is selected from the group consisting of calciumcarbonate, barium sulfate, coal fly ash, iron oxide, and combinationsthereof.

In one embodiment, the step of combining the synthetic turf fragmentswith at least one modifier, filler, or colorant occurs in the extruder.In another embodiment, the step of combining the synthetic turffragments with at least one modifier, filler, or colorant includesconveying the synthetic turf fragments to a blender, conveying the atleast one modifier, filler, or colorant to the blender, and mixing thefragments and the at least one modifier, filler, or colorant in theblender. In yet another embodiment, the steps of conveying the syntheticturf fragments to the blender and conveying the at least one modifier,filler, or colorant to the blender occur concurrently. In oneembodiment, the steps of conveying the synthetic turf fragments;conveying the modifier, filler, or colorant; and mixing are continuous.

In one embodiment, the method further includes passing the extrudatethrough chilled rollers prior to cutting the extrudate into pieces. Inanother embodiment, the step of passing the extrudate through chilledrollers includes pressing and densifying the extrudate. In yet anotherembodiment, the method further includes passing the extrudate through achilled water bath prior to cutting the extrudate into pieces.

In one embodiment, the step of extruding the mixture includes forcingthe mixture through a slot.

In another embodiment, the step of extruding the mixture is continuous.

In one embodiment, the step of cutting the extrudate into piecesincludes cutting the extrudate into strands and cutting the strands intopellets.

In another embodiment, the method further includes removing infill fromthe synthetic turf fragments before combining them with the modifier,filler, or colorant.

In one embodiment, the synthetic turf includes face fibers, a primarybacking, and a primary coating. In another embodiment, the face fiberscomprise polyethylene, polypropylene, nylon, or a combination thereof.In yet another embodiment, the primary backing comprises polyester orpolypropylene or combinations thereof. In one embodiment, the primarycoating comprises polyurethane, latex, hot melt, or a thermoplastic orcombination thereof.

In one embodiment, the polyethylene, polypropylene or nylon or thecombination thereof comprise about 19 wt % to about 80 wt % of thesynthetic turf fragments. In another embodiment, the polyester orpolypropylene or the combination thereof comprise about 1 wt % to about25 wt % of the synthetic turf fragments. In yet another embodiment, thepolyurethane, latex, hot melt, or the thermoplastic, or the combinationthereof comprise about 15 wt % to about 80 wt % of the synthetic turffragments.

In one embodiment, pellets are formed using the method described above.In another embodiment, an infill is formed from the method describedabove. In yet another embodiment, the infill further includes a filler,sand, or rubber, or a combination thereof.

In one embodiment, a synthetic turf is formed using the method describedabove. In another embodiment, an object is formed using the methoddescribed above including the pellets, wherein the object is an athleticfield, tennis court, landscaping, putting green, a backing, track,playground material, baseboard, fiber, or a container.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features, aspects, and advantages of the present disclosure willbecome better understood by reference to the following detaileddescription, appended claims, and accompanying figures, wherein elementsare not to scale so as to more clearly show the details, wherein likereference numbers indicate like elements throughout the several views,and wherein:

FIG. 1 is a flow chart of a process for recycling synthetic turf; and

FIG. 2 is a flow chart of a specific embodiment of the process forrecycling synthetic turf.

DETAILED DESCRIPTION

Various terms used herein are intended to have particular meanings. Someof these terms are defined below for the purpose of clarity. Thedefinitions given below are meant to cover all forms of the words beingdefined (e.g., singular, plural, present tense, past tense). If thedefinition of any term below diverges from the commonly understoodand/or dictionary definition of such term, the definitions belowcontrol.

Embodiments of this invention provide methods of recycling and reusingan existing synthetic turf or a portion of an existing synthetic turf.Other embodiments of this invention provide infill for a synthetic turfwherein the infill is recyclable and can be incorporated into asynthetic turf such that the synthetic turf may be recycled and reused.

Synthetic Turf

Typically, the synthetic turf to be recycled with the present methodincludes a pile fabric having a backing and a plurality of upstandingribbons, also called face fibers or filiform formations, resemblinggrass. Typically, the upstanding ribbons are made of polyethylene,polypropylene or a blend thereof. The ribbons may also be made of nylonor any other material known in the art alone or in combination withpolypropylene and/or polyethylene. These face fibers are tufted or sewninto a primary backing material which can be made of a number ofdifferent materials including, but not limited to, polypropylene andpolyester. A primary coating material, or precoat, is applied to thefiber and primary backing to hold the face fibers in place. The primarycoating of most synthetic turfs includes polyurethane and also typicallyincludes a filler such as calcium carbonate or coal fly ash. Primarycoatings may also include latex, hot melt adhesives, and/orthermoplastics in addition to or instead of polyurethane. Syntheticturfs may also have a secondary coating which may be similar to theprimary coating described herein. Synthetic turfs may also have asecondary backing which can be made of a number of different materialsincluding, but not limited to, polypropylene and polyester.

The face fibers typically make up from about 19 wt % to about 80 wt % ofa synthetic turf. The primary backing typically makes up from about 1 wt% to about 25 wt % of a synthetic turf. The primary coating typicallymakes up from about 15 wt % to about 80 wt % of a synthetic turf.

Synthetic turf may also include an infill material dispersed among theupstanding ribbons, which acts as a ballast and/or contributes to thephysical properties of the turf, such as resiliency, that make the turfsuitable for a particular use. Synthetic turf infill may be made of anymaterial suitable for providing desired physical properties for thesynthetic turf, but most often includes materials such as sand, gravel,cork, polymer beads, and rubbers, including but not limited to crumbrubber, ethylene propylene diene monomer (EPDM) rubber, and neoprenerubber.

The face fibers may include polyethylene, polypropylene, nylon, or othermaterials singly or in combination. The face fibers may include fromabout 0 wt % to about 100 wt % polyethylene, from about 0 wt % to about100 wt % polypropylene, and from about 0 wt % to about 100 wt % nylon.In some embodiments, the face fibers include blends of polypropylene(PP) and polyethylene (PE) in any of the following ratios of PP:PE-5:95;10:90; 50:50; 90:10; 95:5 or any ratio that is within these ranges ofratios. In some embodiments, the face fibers include blends of PP andnylon in any of the following ratios of PP:nylon-5:95; 10:90; 50:50;90:10; 95:5 or any ratio that is within these ranges of ratios. In someembodiments, the face fibers include blends of PE and nylon in any ofthe following ratios of PE:nylon-5:95; 10:90; 50:50; 90:10; 95:5 or anyratio that is within these ranges of ratios. In some embodiments, theface fibers include blends of PP, PE, and nylon in any of the followingratios of PP:PE:nylon-10:10:80; 10:80:10; 80:10:10; 33:33:33 or anyratio that is within these ranges of ratios.

The primary backing may include polyester, polypropylene, and othermaterials singly or in combination. The primary backing may include fromabout 0 wt % to about 100 wt % polyester or from about 0 wt % to about100 wt % polypropylene. In some embodiments, the primary backingincludes blends of PP and polyester in any of the following ratios ofPP:polyester-5:95; 10:90; 50:50; 90:10; 95:5 or any ratio that is withinthese ranges of ratios.

The primary coating may include polyurethane, latex, hot melt adhesive,and/or thermoplastics alone or in combination. Suitable hot meltadhesives include, but are not limited to, Reynolds 54-041, Reynolds54-854, DHM 4124 (The Reynolds Company P.O. Greenville, S.C., DHMAdhesives, Inc. Calhoun, Ga.). Suitable thermoplastics include, but arenot limited to polypropylene, polyethylene and polyester. The primarycoating may also include a filler that may be coal fly ash, calciumcarbonate, iron oxide, or barium sulfate, or any other filler known inthe art. The primary coating may include from about 0 wt % to about 100wt % polyurethane, from about 0 wt % to about 100 wt % latex, from about0 wt % to about 100 wt % hot melt adhesive, and/or from about 0 wt % toabout 100 wt % thermoplastic. The primary coating may include from about0 wt % to about 80 wt % filler. In some embodiments, the primary coatingincludes polyurethane, latex, or thermoplastic and from about 20 wt % toabout 80 wt % filler, or from about 40 wt % to about 60 wt % filler. Inother embodiments, the primary coating includes hot melts and from about0 wt % to about 50 wt % filler, or from about 1 wt % to about 25 wt %filler. Several embodiments of primary coating and secondary backingcompositions are shown below in Table 1.

TABLE 1 Polyurethane Latex Hot Melt Polypropylene Polyester Sample wt %wt % wt % wt % wt % 1 10-70 10-40 5-40 2 30-97 3-70 3 10-70 10-40 5-40 430-97 3-70 5 10-70 10-40 5-40 6 30-97 3-70 7 30-97 3-70 8 10-70 10-405-40 9 30-97 3-70 10 30-97 3-70

Methods of Recycling Synthetic Turf

The methods described herein may be used to recycle and reuse syntheticturf, including turf described above, or other synthetic surfaces havingchemical make-up similar to synthetic turf.

Recycling synthetic turf begins with the removal of the material fromthe point of installation. Typically for a sports field, the syntheticturf is installed by unrolling a 15 foot wide by 150 foot long strip ofturf. A field typically requires multiple rolls, which are laid out onthe field side by side and seamed together to form the field. Infill isthen installed. The infill may be one or more of sand, rubber, and/orany other suitable material as described previously. When a syntheticturf is removed, typically some of the infill is separated from theremainder of the infill. The infill may be removed prior to the removalof the turf or at the same time. For example, a machine may collect theinfill and place it into a container or onto the field. The turf andinfill may be removed at the same time by a machine or by hand. Theindividual strips of turf may be re-rolled and shipped to a recyclingfacility. Alternatively, the strips of turf may be cut and optionallymuch of the infill is dumped out. The turf then may be downsized intosections (e.g., 1 foot by 1 foot for ease and efficiency of shipping).The downsizing may be accomplished by hand or machine. The machine maybe large or small and may use rotary blades or knives or any of avariety of different methods known in the art. The downsized pieces aretypically placed on pallets and shipped to a recycling facility. Priorto recycling the pieces may be downsized even further to a size suitablefor the recycling equipment being used. The turf pieces may be downsizedusing any method known in the art (e.g., cutting, chopping, shredding,pulling, and the like). A suitable size for the turf pieces forrecycling depends on the extrusion equipment being used, and a person ofskill in the art familiar with that equipment is familiar with the sizeof material that is appropriate. Turf pieces that are ready forrecycling are referred to herein as turf fragments. The sizes of theturf fragments are highly variable. Likewise, the turf fragments mayhave any shape. The turf fragments may include very small particles, orfines, that are almost dust-like, but also may include small irregularlyshaped particles having a longest dimension of up to about 0.25 to 0.5inch, and in many cases also may include ribbons of material havingwidths of less than 0.25 inch, but lengths up to about 2 inches. In someembodiments the very small particles, or fines, make up about 5% or lessof the turf fragments. The turf fragments typically are a loosely packedlow density solid material.

Initial efforts to convey the low density turf fragments resulted inclogging and inconsistency in weight of material delivered to theextruder port. Conveyance of low density turf fragments was noteffective with standard equipment. Specific problems with conveyance ofthe low density turf fragments included bridging and clumping of thematerials, which in some cases caused the weight of material deliveredto the extruder to vary and in the worst cases prevented conveyance ofthe material altogether.

Continuous feeding of particulate materials often results in bridging(also called arching) and rat-holing of the materials which can causeintermittent or inconsistent flow through the process. Bridging and ratholing may occur when a particulate material is being discharged from avessel (e.g., a silo, bin, hopper, or the like). Bridging or archingoccurs when the particles near the outlet of the vessel discharge, butparticles more distant from the outlet mechanically lock or form bondswith each other, thereby creating an obstruction in the form of a bridge(or arch) over the outlet so that no more material may pass through theoutlet. Rat-holing occurs when particles directly over the outlet of avessel discharge creating a channel directly over the outlet, andparticles outside the channel have sufficient cohesive strength thatthey do not enter the channel and do not discharge from the vessel.Bridging and rat-holing are typically associated with fine particulatematerials such as powders.

Clumping can occur when particles of a low density material accumulateto such an extent that the weight of the accumulated particles densifiesthe material at the bottom of the mass, causing the particles to packtogether and preventing the particles from flowing. Clumping cancontribute to bridging.

Problems with conveyance of the turf fragments were overcome by use ofmechanical material flow aids. A variety of material flow aids arecommercially available from companies such as, but not limited to,Chicago Vibrator Products (Westmont, Ill.), Thayer Scale (Pembroke,Mass.), FMC Technologies, Inc. (Tupelo, Miss.), K-Tron (Pittman, N.J.),Horizon Systems, Inc. (Lawrence, Kans.), Mine & Process Service, Inc.(Kewanee, Ill.), and Jenike & Johanson, Inc. (Tyngsboro, Mass.). Theseflow aids typically make use of vibrators, baffles, screens, directedair flow or combinations thereof to convey consistent weights ofparticulate materials through a process. We developed and used amechanical system to maintain good conveyance of the turf fragmentsthrough the process. In some embodiments, bins or hoppers includedrollers having external spikes or baffles that rotated among the turffragments to constantly or intermittently blend the fragments andthereby prevent clumping and bridging. Using such equipment allowedconveyance of the low density turf fragments through the process.Adjusting process parameters such as flow rate also aided in movingmaterial in a more consistent manner.

Extruding the synthetic turf material initially posed problems includingoff-gassing that was due to the dissimilar materials such as nylons,filers, and thermoplastics, all having different melt characteristics.The significant amount of gas in the extrudate caused the extrudate todecrease in density upon exiting the extruder. This lower densitymaterial clogged the orifices, and broke when extruded as strands.Underwater pelletizing lessened the problems, but was limiting inparticulate size and shape. The problems with off-gassing were overcomeby modifying or adding one or more processing steps. In someembodiments, the orifices at the exit of the extruder that were cloggingwere replaced with a slot to alleviate clogging. In some embodiments,the blown or gas-entrapped film created by the off-gassing was passedthrough chilled rollers to press and re-densify the extrudate. In someembodiments, the re-densified extrudate was then passed through achilled water bath. Use of one or more of such processing steps providedan extrudate having the desired properties that optionally could be cutinto strands and/or pellets.

Additives

One method of recycling synthetic turf includes combining synthetic turffragments with at least one additive, which is a modifier, filler, orcolorant to form a mixture; and extruding the mixture to form anextrudate. The extrudate optionally is then size reduced. In someembodiments, the step of combining the turf and the additive includesconveying the turf fragments and the additive to a blender, mixing theturf fragments and the additive in the blender, and removing theturf/additive mixture from the blender. In some embodiments thesynthetic turf fragments and the additive are separately butconcurrently conveyed into the blender. In some embodiments, the methodis carried out as a continuous process.

In some instances, it is desirable to add one or more fillers,modifiers, colorants, or other additives to the turf fragments prior toextrusion. In some embodiments, these additives may aid in extrusion ofthe turf fragments and/or impart desired properties to the extrudedproduct. Accordingly, in one embodiment of the present disclosure thedisclosed method includes the step of combining the turf fragments withat least one filler, modifier, colorant or other additive. Theseadditives may be added prior to or during the extrusion process. Whenthe additives are added prior to extrusion, they are premixed with theturf fragments and added to the extruder. One of skill in the art candetermine for a given process whether it is advantageous to add theadditives prior to or during extrusion. One factor in this determinationis the type of extruder used. For example, twin screw extrudersefficiently mix the turf fragments and additives together duringextrusion.

Fillers may include but are not limited to calcium carbonate, coal flyash, iron oxide, barium sulfate, or other fillers known in the art.Modifiers, colorants, or other additives that are suitable for use withthe present invention include, but are not limited to, plasticizers,elastomers, compatibilizers, colorants, antimicrobials, and UVstabilizers. Examples of modifiers that can be used are the following:wax; EPDM rubber; high and low density polyethylene; high and lowdensity polypropylene; Exxon Vistamaxx 6102, Exxon Vistamaxx 3000, ExxonPX 9361, and Exxon PX 9371 (all available from Exxon Mobile ChemicalPolymer Group, Houston, Tex.); Faraprene 381-35A (available from O'NeilColor and Compounding, Jasper, Tenn.); SureFlo 3001E and SureFlo 3001N(available from Flow Polymers, Inc., Cleveland, Ohio); and any number ofother modifiers. Suitable colorants include dyes and pigments. Red,green, blue, black or any number of different colors can be added.However, in some embodiments, colorants may have very little effect dueto the dark nature of the material.

The additive may be any material that imparts the desired properties andin some embodiments may be pre- or post-consumer waste. Post-consumerwaste includes a product (or part of a product) that has been used forits intended end-use purpose and has been discarded or otherwise removedfrom use. By contrast, pre-consumer waste includes manufacturing scrapor a defective product that has never been used by a consumer. As oneexample, carpet scrap, either pre- or post-consumer waste, if reduced toan appropriate size may be used as an additive. The carpet scrap shouldbe reduced in size to a size similar to the size of the turf fragments.The components of the carpet scrap, which typically include nylonfibers, latex, polyurethane, polypropylene, can function as the fillersor modifiers described above. For example, the polypropylene canfunction as a modifier and the latex and polyurethane can function asfiller. Using carpet scrap thus imparts desired properties to therecycled turf material and also provides a use for waste that wouldotherwise go to a landfill.

In some embodiments, synthetic turf fragments make up from about 10 wt %to about 90 wt % of the material that is extruded. In some embodiments,the amount of filler added prior to or during extrusion is from about 10wt % to about 90 wt % of the material that is extruded. In someembodiments, the amount of filler added prior to or during extrusion isfrom about 10 wt % to about 70 wt % or from about 10 wt % to about 50 wt% of the material that is extruded. In some embodiments, the amount ofmodifier added prior to or during extrusion is from about 10 wt % toabout 90 wt % of the material that is extruded. In some embodiments, theamount of modifier added prior to or during extrusion is from about 10wt % to about 70 wt % or from about 10 wt % to about 50 wt % of thematerial that is extruded. In some embodiments, the amount of colorantadded prior to or during extrusion is from about 1 wt % to about 10 wt %of the material that is extruded.

The step of extruding the mixture of synthetic turf fragments andadditive may be carried out with any equipment suitable for extrusion orknown to one of skill in the art. A number of different extruders may beused for this process depending upon the type of mixing or heating thatis desired. Examples of suitable extruders include single screw and twinscrew extruders. The twin screw extruder can have co-rotating or counterrotating screws and the single screw extruder has one rotating screw.The screws can be designed for different purposes but have the capacityto heat and mix the material. Extruders typically have variable screwspeeds and variable heating as well as variable feed rates. Theappropriate speed and heat rate is determined by the type of outputdesired.

Extrusion is carried out at elevated temperatures. In some embodimentsthe temperature during extrusion is between about 200° F. and about 500°F., or between about 250° F. and about 450° F. In some embodiments thetemperature during extrusion is between about 350° F. and about 400° F.In some embodiments the rate of extrusion is from about 3 to about 2,000lbs/hour, or from about 100 to about 500 lbs/hour, or from about 300 toabout 500 lbs/hour.

Extrusion can be carried out using any size die that will provide aproduct of the desired size and shape, but in some embodiments iscarried out using a die that has an aperture in the shape of a slot. Thesize of the slot may vary depending on the size of the extruder, thesize of the available cutting equipment, and/or the desired use of theextrudate. One of skill in the art can easily determine the appropriatesize of the slot based on the available equipment and desired end use ofthe product.

In some embodiments upon exiting the die the extrudate is passed throughchilled rollers. In some embodiments the rollers are chrome plated,jacketed, and chilled by running chilled fluid or fluid mixture (e.g.,water) through the rollers. These chilled rollers typically are at atemperature between 55° F. and 85° F. In some embodiments the chilledrollers are at a temperature between 65° F. and 75° F. When theextrudate passes through the chilled rollers it becomes more dense.Different combinations of starting materials for the extrusion processproduce extrudates having different densities coming out the extruderand result in different changes in density as the extrudate passesthrough the chilled rollers. By way of example only, however, in someembodiments, upon passing through the chilled rollers, the density ofthe extrudate changes from between about 35 and 50 lbs/ft³ to betweenabout 60 and 80 lbs/ft³. In some embodiments, upon passing through thechilled rollers, the density of the extrudate changes from between about40 and 45 lbs/ft³ to between about 70 and 75 lbs/ft³. In someembodiments, the extrudate is passed through a chilled fluid bath (e.g.,water or water mixture). The fluid bath is at a temperature between 55°F. and 80° F. In some embodiments the temperature of the bath is between65° F. and 75° F. The extrudate typically remains in the bath between 10and 30 seconds. In one embodiment, the extrudate remains in the bathabout 15 seconds. One of skill in the art can easily determine theoptimal temperature for an extrudate having a desired end use.

In some embodiments, the extrudate is cut into pellets or granules. Insome embodiments the extrudate is cut by a pelletizer that slices theextrudate into strips, then dices the strips into pellets. One suchpelletizer is produced by Henion Dicing Products, LLC (Kennesaw, Ga.).One potential use of the pellets is as infill for other synthetic turfinstallations, but other uses are contemplated as well, such asplayground material, fill for the sub-base of an athletic track, rawmaterial for injection molding or extrusion, as a component of a backingor baseboard, or as a packing material. To produce pellets of a desiredsize and/or shape the extrudate may be cut once or more than once. Forexample, the extrudate may be cut into strips and then those strips maybe cut into pellets. In some embodiments, the final product of theextrusion step includes pellets of any desired shape including, but notlimited to, spherical, cylindrical, cubical, rhomboidal, oroval/football shaped. The pellets may also be of an irregular shape.This irregular shape might be advantageous, for example, to aid tightpacking of the granules.

The size and quantity of the pellets produced depends upon the speed ofthe extruder and the cutting system. The size of the pellets may varysubstantially depending on the intended use and the methods of thecurrent invention are suitable for producing pellets in a wide varietyof sizes. For example, in some embodiments, the pellets may be a cubeabout 1 inch (in.) (2.54 cm) per side or may be of another shape withtheir longest dimension about 1 in. (2.54 cm). As one example, suchpellets may be useful in injection molding. In some embodiments, thepellets may be smaller, with their longest dimension less than about 0.4in. (1 cm). As one example, such pellets may be useful as infill forsynthetic turf. In some embodiments, pellets intended for use assynthetic turf have sizes that vary from 0.05 mm to 9 mm across theirlongest cross-section. In some embodiments, the sizes of those pelletsvary from 1 mm to 6 mm or from 1 mm to 3 mm across their longestcross-section. In some embodiments, the pellets are between around 25pellets per gram and 400 pellets per gram. In one embodiment the pelletsare around 200 pellets per gram and each have an oblong shape (e.g., afootball shape).

As an example of the extrusion process, in one non-limiting embodiment,synthetic turf fragments are mixed with post-consumer polyethylene,which functions as a modifier; polyurethane, which functions as afiller; and Exxon Vistamaxx 6102, which functions as acompatibilizer/modifier. The mixture includes about 60 wt % turffragments, about 20 wt % polyethylene, about 10% polyurethane, and about10% Vistamaxx. The mixture is poured into the feed system of anextruder. The mixture is heated to approximately 500° F. and mixed atapproximately 68 RPM. The duration of mixing relates to the size of theextruder and the speed of operation. The mixture is then pushed out ofthe extruder by the screws through a plate on the end of the extruder.The plate has a slot with dimensions approximately 3.5 inches wide andapproximately 0.25 inches high, through which the material is extruded.A ribbon of extruded material is produced. The ribbon is then pressedand densified by chilled rollers and cooled in a water bath. Thedensified ribbon is drawn into a cutter where it is cut into strips thatare then cut into pellets. The pellets are approximately 3 mm to about 6mm across their largest cross-section.

In one embodiment, the disclosed method further includes the step ofseparating at least 90% (wt) of non-recyclable components from thesynthetic turf before the step of mixing the synthetic turf fragmentswith the additive. Many conventional synthetic turfs include largequantities of infill materials such as sand, gravel, and rubber. Thesematerials, however, are not generally considered recyclable and are notfavored for use in the recycling method described herein. Accordingly,in some instances, it may be desirable to remove at least some of theinfill, or other components, of an existing synthetic turf beforesubjecting that synthetic turf to the recycling method described above.Separating the non-recyclable infill or other non-recyclable componentsmay be accomplished before or after the synthetic turf is size reducedto turf fragments. In some embodiments, a portion of non-recyclableinfill material is separated from the remaining synthetic turf. In someembodiments, at least 80% (wt) of the non-recyclable infill material isseparated from the remaining synthetic turf. In some embodiments, atleast 90% (wt) of the non-recyclable infill material is separated fromthe remaining synthetic turf. In some embodiments, at least 95% (wt) ofthe non-recyclable infill material is separated from the remainingsynthetic turf. In some embodiments, at least 98% (wt) of thenon-recyclable infill material is separated from the remaining syntheticturf.

One of skill in the art would recognize that the methods disclosedherein are not limited to use with synthetic turf, but are suitable forrecycling other products made of similar materials.

Embodiments of this invention also provide infill for a synthetic turf.In some embodiments, the infill includes a material (for exampleparticles or pellets) made from recycled synthetic turf. The termsparticle and pellet are used interchangeably herein. In someembodiments, the infill is made by a process described herein.

In one embodiment the infill is a pellet or particle that is a mixtureof (a) polyethylene, polypropylene, or nylon or a combination thereof;(b) polyester or polypropylene or a combination thereof; or (c)polyurethane, latex, hot melt, a thermoplastic, polypropylene orpolyethylene or a combination thereof; or, a combination of (a), (b),and (c). The pellets may include any component used in a synthetic turf,including but not limited to components used as the face fibers, theprimary backing, the primary coating, and the infill as describedpreviously herein. In some embodiments, sand, gravel, and rubber arepresent only as impurities and make up less than about 5 wt % of theinfill pellets. In some embodiments, sand, gravel, and rubber make upless than 2 wt % of the infill pellets. In some embodiments, sand,gravel, and rubber are not present in the infill pellets.

In some embodiments the infill pellets of the present invention include:from about 19 wt % to about 80 wt % PE, PP, or nylon, or a combinationthereof; from about 1 wt % to about 25 wt % PP or polyester, or acombination thereof; and from about 15 wt % to about 80 wt %polyurethane, latex, hot melt, or thermoplastic, or a combinationthereof.

In some embodiments, infill pellets of the present invention includefrom about 10 wt % to about 90 wt % of recycled synthetic turf material.The percentage of recycled material in the final product may varydepending on the intended use for the pellets. For example, if morefiller or modifier is required for a given use, the percentage of fillerwould be higher and the percentage of recycled material in the pelletswould necessarily be lower. In some embodiments the infill functions asa ballast material. This infill may need more filler to increase thespecific gravity of the pellets. In other embodiments, a material to beused as an infill for a playing surface may require less filler, but mayalso require additives for softness. The increased percentage ofadditives will influence the percentage of recycled material in theinfill.

The pellets may be any desired shape. For example, in some embodimentsthe pellets can be substantially spherical, cylindrical, cubical,rhomboidal, oval/football shaped, or may be an irregular shape.Different shapes may be advantageous for different uses. For example,irregularly shaped pellets may pack more efficiently than regularlyshaped pellets. The extent of packing of the pellets can affect thephysical properties of a synthetic turf that includes the pellets. Thepellets may be any desired size and one of skill in the art can easilydetermine an appropriate size for the desired end use of the pellets.

The physical properties of the pellets described herein can be adjustedby one skilled in the art at least by varying the size of the pellets,the shape of the pellets, and/or the composition of the pellets. Forexample, one of skill in the art would understand that the properties ofthe pellet may be adjusted by adjusting the amount of filler, additive,and/or modifiers. Thus, the pellets described herein can be made to haveany desired physical property and are, thus, suitable for use in anysynthetic turf.

Another embodiment of the invention is a synthetic turf that includesany of the pellets described above. This synthetic turf is suitable fora variety of uses, including but not limited to, athletic fields,landscaping, dog runs, putting greens, jogging paths, paintball fields,tennis courts, and playgrounds. Desired properties for a synthetic turfvary depending on the intended use of the turf. For example, dependingon the intended use of the turf, one might prefer a softer surface(e.g., for playgrounds), a harder surface (e.g., for putting greens), ora surface that allows ideal ball bounce and/or ball roll (e.g., forathletic fields). Pellets described herein can be used to impart avariety of advantageous properties to synthetic turfs.

In some embodiments, a synthetic turf including infill pellets asdescribed herein may also include another type of infill. This othertype of infill may be any other infill used in synthetic turf includingbut not limited to sand, gravel, cork, polymer beads and rubbers. Insome embodiments, multiple types of infill may be mixed together in asingle layer in the synthetic turf. In other embodiments multiple typesof infill may be disposed in a synthetic turf individually as discretelayers. Still other embodiments may include some combination of mixingand layering different types of infill.

FIG. 1 is a flow chart showing a process for recycling synthetic turf.The synthetic turf fragments ready for recycling are optionally removedof infill and then mixed with at least one additive, the additive beinga modifier, filler, or a colorant. The turf fragment and additivemixture is then extruded into an extrudate, the extrudate then being cutinto pellets.

FIG. 2 is a flow chart showing a specific non-limiting embodiment of theprocess for recycling synthetic turf of the present invention. A mixtureincluding approximately 60% turf waste to be recycled, approximately 20%Exxon Vistamaxx, approximately 10% polyethylene, and approximately 10%polyurethane is mixed before entering an extruder. The resultingextrudate is rolled with chilled rollers, passed through a chilled waterbath, and then pelletized.

The following examples will serve to further illustrate the presentinvention without, at the same time, however, constituting anylimitation thereof. On the contrary, it is to be clearly understood thatresort may be had to various embodiments, modifications and equivalentsthereof which, after reading the description herein, may suggestthemselves to those skilled in the art without departing from the spiritof the invention.

Example 1

Synthetic turf fragments, 60%; Exxon Vistamaxx, 10%; polyurethane, 10%;and polyethylene, 20% were mixed together. The mixture was processedthrough a twin screw extruder having the temperature profile below:

TABLE 2 Zone Temp (° F.) 1 500 2 500 3 500 4 500 5 500 6 450

where zone 1 includes the entry port and zone 6 includes the exit, andthe zones are of equal length and distributed along the length of theextruder from the entry to the exit. The material was extruded through adie having an aperture in the shape of a slot. The extrudate was passedthrough chilled rollers at a temperature between about 75° F. to 85° F.,then through a chilled water bath at a temperature between about 65-75°F. The extruded material was at a temperature of about 475° F. comingout of the slot and about 75° F. coming out of the water bath. Theextrudate produced had a breaking strength of 165.7 lbs/inch and anelongation of 20.8% measured according to ASTM 2256.

Example 2

Synthetic turf fragments, 60%; Exxon Vistamaxx, 20%; polyurethane, 10%;and polyethylene, 10% were mixed together. The mixture was processedthrough a twin screw extruder having the temperature profile inExample 1. After extrusion, the extrudate was processed as explained inExample 1. The extrudate produced had a breaking strength of 148.7lbs/inch and an elongation of 18.3% measured according to ASTM 2256.

Example 3

Synthetic turf fragments, 60%; Exxon Vistamaxx, 15%; polyurethane, 7.5%;polyethylene, 7.5%; and carpet scrap, 10% were mixed together. Themixture was processed through a twin screw extruder having thetemperature profile in Example 1. After extrusion, the extrudate wasprocessed as explained in Example 1. The extrudate produced had abreaking strength of 217 lbs/inch and an elongation of 16.3% measuredaccording to ASTM 2256.

Example 4

Synthetic turf fragments, 60%; Exxon Vistamaxx, 16%; polyurethane, 10%;and polyethylene, 14% were mixed together. The mixture was processedthrough a twin screw extruder having the temperature profile inExample 1. After extrusion, the extrudate was processed as explained inExample 1. The extrudate produced had a breaking strength of 147.6lbs/inch and an elongation of 31.1% measured according to ASTM 2256.

The foregoing description of preferred embodiments of the presentdisclosure has been presented for purposes of illustration anddescription. The described preferred embodiments are not intended to beexhaustive or to limit the scope of the disclosure to the preciseform(s) disclosed. Obvious modifications or variations are possible inlight of the above teachings. The embodiments are chosen and describedin an effort to provide the best illustrations of the principles of thedisclosure and its practical application, and to thereby enable one ofordinary skill in the art to utilize the concepts revealed in thedisclosure in various embodiments and with various modifications as aresuited to the particular use contemplated. All such modifications andvariations are within the scope of the disclosure as determined by theappended claims when interpreted in accordance with the breadth to whichthey are fairly, legally, and equitably entitled.

What is claimed is:
 1. A method for recycling synthetic turf comprisingthe steps of: (a) combining a plurality of synthetic turf fragments withat least one modifier, filler, or colorant to form a mixture wherein theturf fragments include infill contained therein; (b) removing from atleast 80% to at least 98% of the infill from the synthetic turffragments before combining them with the modifier, filler, or colorant;(c) extruding the mixture to form an extrudate; and (d) cutting theextrudate into pellets.
 2. The pellets made by the method of claim
 1. 3.An infill comprising the pellets of claim
 1. 4. The infill of claim 3,further comprising a filler, sand or rubber, or a combination thereof.5. A synthetic turf comprising the infill of claim
 3. 6. An objectcomprising the pellets of claim 1, wherein the object is selected fromthe group consisting of an athletic field, a tennis court, landscaping,a putting green, a backing, a track, playground material, a baseboard,fiber, and a container.